The invention relates to a writing unit for a cartridge fountain pen, in particular a writing unit for a cartridge fountain pen which includes an ink feeder, a writing nib mounted to the forward end portion of the ink feeder, and a gripping piece enclosing the rearward end portion of the ink feeder. Also, a capillary gap extends along the length of the ink feeder to the writing nib, and an air channel overlies the capillary gap in the radical direction.
Cartridge fountain pens with writing units of the kind under discussion have been known for decades. Cartridges which are filled and closed with a ball at the manufacturer's end, are pierced open for use by means of a pin of the writing unit, the ball which serves as a closure, being pushed into the interior of the cartridge for tapping the cartridge. Even after the cartridge fountain pens under discussion have been introduced for decades, the initial writing in particular with a new or clean cartridge fountain pen continues to be extremely problematic. On the one hand, with conventional writing units or respectively the ink feed systems used therein, it takes minutes and thus too long, after the cartridge is tapped, for the ink to reach the nib point, and for all capillaries important for a satisfactory function to fill with ink.
On the other hand, the risk is incurred after tapping the cartridge that ink leaks out, since while the capillary longitudinal gap of the ink feed system fills with ink immediately after the tapping, i.e., it supplies the nib with ink, the control zone which is important for a regulation of the ink flow and thus serves quasi as a fluid valve, has not yet been filled with ink, thereby allowing air to flow continuously into the cartridge and thus permitting the ink to reach the nib uncontrolled or unmetered. The consequence of ink dripping from the nib exists in particular when, after having been tapped, the cartridge fountain pen is put into a desk stand or placed into a box for shipping.
Until now, leading manufacturers of cartridge fountain pens have offered to eliminate the aforesaid problem in that they equip their fountain pens with cartridges already at plant site, and the cartridge fountain pens thus reach the retail trade in a form ready for writing. Often, the prolonged process of a writing start is shortened by the manufacturer in that the cartridge fountain pens with the cartridge tapped are treated in a centrifuge. Although this relieves a dealer from the time-consuming tapping of the cartridge and the initial writing of the fountain pen, the risk of leakage is especially great during transportation which is normally not free of vibration.
In particular, when air transportation is selected, the occurring pressure and temperature differences will lead to a forced leakage of ink especially when the ink feeder is designed for large writing widths, because of expanding ink or air, whereby considerable damage can be caused.
Finally, the so far known writing units, in particular with the use of an ink feeder for large writing widths, are problematic in so far as they offer only little protection against blotting when the throughput of ink is large.
It is therefore the object of the invention to design and further develop the writing unit for cartridge fountain pens of the initially described kind such that, in particular with ink feeders dimensioned for large writing widths, first, a dripping or a leaking of ink after tapping the cartridge is prevented and the procedure is accelerated, and, second, a blotting is largely prevented at pressure and temperature fluctuations.